In recent years, developments of human interface devices have been accelerated that use gestures, as an input means, which are movements of human bodies including hands and arms. Such interface devices receive a user's gesture as an input and recognize the gesture to respond thereto with video, sound or operation of an apparatus.
An interface device using a gesture as an input means has a three-dimensional object-measurement device which measures a distance between each point (such as each part of a user's body) on a three-dimensional object by which an input is applied and the device itself. The above interface device repeats measurement of a distance between each part of a user's body and the device itself by using the three-dimensional object-measurement device and recognizes user's movements based on a change of the distance. Various three-dimensional object-measurement devices have been recently developed.
The device recited in Patent Literature 1 calculates a distance to a target to be measured by using triangulation. The above device includes a pattern generator which generates a light with a random pattern and a camera which images a reflected light which is a light irradiated from the pattern generator and reflected on a target to be measured. Then, based on a position of each pattern in an obtained image, a distance to a target to be measured is calculated based on triangulation.
The device recited in Patent Literature 2 calculates a distance to a target to be measured in the following manner. First, the above device splits a laser beam into a plurality of laser beams. Next, with respect to each of the split laser beams, the above device changes a focal length of each laser beam such that each laser beam converges only on one axis differing on a plane perpendicular to a progressing direction of the laser beam and each laser beam has a different focal length. Then, the above device images a reflected light obtained as a result of reflection of all the split laser beams on an object to be measured, and calculate a distance to the object to be measured based on a cross-sectional shape of the reflected light.
The position measuring method recited in Patent Literature 3 is a method for calculating a distance to an object to be measured by imaging a measurement target by zooming at different magnifications a plurality of times and comparing the positions of the same point on the object to be measured in the images as a result of imaging.
The device recited in Patent Literature 4 is a three-dimensional measurement device which obtains a shape of a surface of a subject three-dimensionally. The above device has an imaging means to image a subject a plurality of times. Specifically, the above device images a subject while adjusting a focus and zooming of the imaging means for each of xy coordinates on an xy plane forming an image frame. Then, the above device calculates a z coordinate of a surface of the subject in each of the xy coordinates based on an imaging result.
The device recited in Patent Literature 5 calculates a distance to each part of an object to be measured using a plurality of confocal optical systems having different focal positions. The above confocal optical system is configured with a laser beam source and a photoelectric sensor. While changing a position of each confocal optical system, the above device irradiates an object to be measured with a laser beam from the laser beam source of each confocal optical system, and scans an object to be measured. Then, the above device measures intensity of a reflected light of a laser beam by a photoelectric sensor of each confocal optical system and, based on the intensity, measures a distance to an object to be measured.
The device recited in Patent Literature 6 irradiates a measurement target with a laser beam and calculates a distance to the object to be measured based on a time from application of the laser beam to the measurement target until a reflected light is sensed by an optical receiver.